En bloc renal transplant from infant donors to adults

OBJECTIVE: To analyze the medium-term outcome of en bloc transplantation of pediatric kidneys into adult patients, including the incidence and type of surgical complications. METHODS: From November 1991 to December 1997, we performed 37 en bloc transplantation of pediatric kidneys into adult patients. The kidneys were harvested from donors less that 3 years old and/or weighing 15 kg. The mean follow-up was 24 months. Grafting was achieved by end-to-side anastomosis of the donor cava to the receptor external iliac and the aortic patch to the external iliac artery. RESULTS: Three grafts failed, probably due to hilar torsion; the remaining were initially functioning well. Seven transplant removal were performed; 6 were due to thrombosis. The actuarial graft survival was 89.1% at one month, 80.83% at 12 months and 80.83% at 24 months. CONCLUSIONS: The medium-term results of en bloc transplantation of pediatric kidneys into adult patients were excellent and demonstrate the efficacy of this type of grafts. Arterial and venous thrombosis were the most important complications, quantitatively and qualitatively.     

Stability and Accuracy of a Finite-Difference Time-Domain Scheme for Modeling Double-Negative Media With High-Order Rational Constitutive Parameters

This paper introduces an extension of the original finite-difference time-domain (FDTD) method for modeling double-negative media characterized by high-order frequency-dependent permittivity and permeability. The approach basically consists of adding electric and magnetic current densities to Maxwell's curl equations and considering Ohm's law as a constitutive relationship. Current densities are discretized by using a weighted average in time and Ohm's law by applying the Mobius transformation technique. The extended FDTD formulation is validated and its numerical features are carefully examined. More specifically, analytical stability conditions are derived for several types of double-negative media and the numerical dissipation issue is discussed. In addition, the numerical dispersion equation for general high-order double-negative media is given and the order of accuracy of the scheme is studied. Finally, the definition of numerical refractive index is addressed and it is shown that, when the discretization parameters of the problem are not properly chosen, a negative refractive index may become a positive one in the discrete world, thus changing the physics of the problem.     

Reviewing 25 Years of Testing Technique Experiments

Mature knowledge allows engineering disciplines the achievement of predictable results. Unfortunately, the type of knowledge used in software engineering can be considered to be of a relatively low maturity, and developers are guided by intuition, fashion or market-speak rather than by facts or undisputed statements proper to an engineering discipline. Testing techniques determine different criteria for selecting the test cases that will be used as input to the system under examination, which means that an effective and efficient selection of test cases conditions the success of the tests. The knowledge for selecting testing techniques should come from studies that empirically justify the benefits and application conditions of the different techniques. This paper analyzes the maturity level of the knowledge about testing techniques by examining existing empirical studies about these techniques. We have analyzed their results, and obtained a testing technique knowledge classification based on their factuality and objectivity, according to four parameters.     

The role of replications in Empirical Software Engineering

Replications play a key role in Empirical Software Engineering by allowing the community to build knowledge about which results or observations hold under which conditions. Therefore, not only can a replication that produces similar results as the original experiment be viewed as successful, but a replication that produce results different from those of the original experiment can also be viewed as successful. In this paper we identify two types of replications: exact replications, in which the procedures of an experiment are followed as closely as possible; and conceptual replications, in which the same research question is evaluated by using a different experimental procedure. The focus of this paper is on exact replications. We further explore them to identify two sub-categories: dependent replications, where researchers attempt to keep all the conditions of the experiment the same or very similar and independent replications, where researchers deliberately vary one or more major aspects of the conditions of the experiment. We then discuss the role played by each type of replication in terms of its goals, benefits, and limitations. Finally, we highlight the importance of producing adequate documentation for an experiment (original or replication) to allow for replication. A properly documented replication provides the details necessary to gain a sufficient understanding of the study being replicated without requiring the replicator to slavishly follow the given procedures.

Numerical analysis of discontinuities in a rectangular waveguide loaded with isotropic or anisotropic obstacles by means of the coupled-mode method and the mode-matching method

A hybrid method obtained as a combination of the coupled-mode method (CMM) and the mode-matching method (MMM) is developed and applied in the analysis of multiple dielectric and magnetic discontinuities in rectangular waveguides. As both are moment methods, some kind of truncation has to be carried out in the computer implementation. It is shown that selection of a different number of modes in the two methods is not necessary, unless low-permittivity meida inside the waveguide are considered. As a consequence, the procedure for slecting the number of basis functions is only done in one of the methods. Numerical examples are presented showing the behaviour of the method and the proofs of convergence. Examples are included illustrating the power of this hybrid technique, especially in relation to non-reciprocal structures containing magnetized ferrites.     

Structural analysis of FRP reinforced polymer concrete material

The paper deals with a study of precast elements made of polyester polymer concrete (PPC) reinforced with glass fibre rebars (GFRP). The paper describes the properties of the materials, which were tested on a microscopic scale using different experimental techniques such as porosimetry, scanning electron microscopy and petrography. Likewise, characterisation in a macro-scale was carried out to define the mechanical properties of the material (modulus of elasticity, stress–strain curve, ultimate strength and bond). Based on the latter properties, a relatively simple method is presented to estimate the ultimate bearing capacity of beams under bending load. The calculation method has been verified by testing beams and full-scale elements.     

Composition of two Spanish common dry beans (Phaseolus vulgaris), ‘Almonga’ and ‘Curruquilla’, and their postprandial effect in type 2 diabetics

BACKGROUND: Legume consumption has been associated with a lower risk of developing type 2 diabetes. However, the type of legume is a modifier of its effect. Two Spanish dry bean varieties—white (‘Almonga’) and cream (‘Curruquilla’)—were analyzed and used in a postprandial study in type 2 diabetics to assess glucose, insulin and triacylglycerol in blood. RESULTS: ‘Curruquilla’ variety had higher total galactoside (stachyose, mainly), trypsin inhibitors and lectin content than ‘Almonga’. The canning liquid was discarded prior to the analysis and the bean consumption by the subjects. The canning process reduced the total α‐galactoside content (>50%), practically eliminated trypsin inhibitors, and no lectin content was found. After bean consumption, maximum glucose was obtained at 60 min and was three times lower than that in bread. After bean intake, maximum insulin was produced 60 min with ‘Almonga’ and occurred later (90 min) with ‘Curruquilla’ and bread. After ‘Almonga’ intake, the area under the curve response of triglycerides was 14% lower compared to bread (P = 0.013). CONCLUSIONS: ‘Almonga’ and ‘Curruquilla’ are similar in the content of the nutritional but not in that of the antinutritional components. Both beans showed similar effects on blood glucose and insulin in type 2 diabetics and marked differences compared to those of bread in terms of magnitude and time course, but only ‘Almonga’ rendered a significant reduction in the triglyceridemic response. © 2012 Society of Chemical Industry     

The Influence of Activated Coal Mining Wastes on the Mineralogy of Blended Cement Pastes

In recent years, kaolinite‐based wastes are focusing the attention of researchers to obtain recycled metakaolinite, with consequent environmental and socioeconomic benefits. One of these lines of research is based on coal mining waste, which once activated thermally, it becomes a highly pozzolanic product (ACM). This study reports the influence of activated carbon mining waste on the formation and evolution of the mineralogical phases in the ACM/cement system as well as their influence on the microstructure up to 90 d of reaction. Mineralogical analyses clearly show that the addition of ACM modified mineralogical compounds of blended cements. The C₄AH₁₃ and C₄AH₁₂ were the predominant phases in this type of cements; while in the ordinary portland cement cements, portlandite, ettringite, and carboaluminate were main hydrated phases. Two differential zones in the pore size distribution of the C–S–H gels at 12 and 4.5 nm were observed, predominating the formation of C–S–H gels at 12 nm when 20% of ACM was added to the cement.     

The pozzolanic properties of paper sludge waste

The use of paper de-inking sludge in pozzolanic material manufacture permits a disposable residue to be included in the cycle of the materials. A study on the reuse of paper de-inking sludge, undertaken in Spain, shows its potential as raw material for yielding a product with pozzolanic activity.

This study establishes that an optimal condition for transforming paper de-inking sludge into a pozzolanic addition is achieved at 700 °C maintained for 2 h. Under these conditions, the organic matter disappears and the calcined sludge becomes active by transforming kaolinite into metakaolinite. The calcined product exhibits high pozzolanic activity.

The present paper also analyses mechanical, physical and chemical properties of a blended cement containing 90% (in mass) standard Portland cement (CEM I-52,5N) and 10% of the pozzolanic addition obtained from controlled calcination of paper de-inking sludge (for 2 h at 700 °C). When the blended cement is compared with a cement containing 100% standard Portland cement, the following conclusions can be mentioned: a significant gain in compressive strength from 7 days on, a sooner initial setting time, as well as a reduction in SO₃ percentage. In any case, the new blended cement complies with requirements set out in Spanish/European standard UNE EN 197-1-Part 1.     

Pre-normative research on the use of mixed recycled aggregates in unbound road sections

This paper presents and discusses the results arising from a pre-normative study aimed at determining the physical, chemical and mineralogical characteristics of mixed recycled aggregates produced from the treatment of mixed rubble for use in unbound structural layers of road. The results of this research show that the combined presence of concrete and ceramic materials induces pozzolanic reactions, which contribute to an increase in the bearing capacity of the compacted mixed recycled aggregate. From an analysis of their chemical characteristics, it can be inferred that the total sulphur compound content, the gypsum content and soluble salt contents can be regulated with reference to the water soluble sulphates test, given the high correlation that exists between those parameters. Generally, mixed recycled aggregates with ceramic material contents below 35%, organic matter contents below 0.8% and water soluble sulphate contents below 0.4% constitute a granular material that is technically feasible for use in unbound structural road sections.